A wind turbine comprises one or more rotor blades. The rotor blades are connected to a hub. The rotor blades and the hub form the rotor of a wind turbine. The wind interacts with the rotor and causes a rotation of the rotor. The rotation of the rotor is transferred to an electrical generator. The rotational energy of the rotor is there transferred into electrical energy.
The rotation of the rotor is often transferred over a shaft. The rotor, the shaft and the rotor of the generator are rotatable in respect to the stationary part of the wind turbine. The hub, and in cases the shaft, need to be connected to the stationary part of the wind turbine by a bearing.
In many wind turbines the rotation of the rotor is directly transferred to the generator without the use of a gear. These wind turbines are called direct driven wind turbines, or direct drive wind turbines.
The weight and the forces acting on the rotor of the wind turbine are transferred over at least one bearing from the rotatable part of the wind turbine to the stationary part. For higher loads a plain bearing, or sliding bearing, is used in the wind turbine.
The forces acting in the sliding bearing under operation lead to wear at the sliding surface. To improve the lifetime and serviceability of the wind turbine, the main bearing is equipped with bearing pads that are exchangeable.
The bearing pads need to be accessible to be exchanged. It is therefore known to remove at least a part of a sliding surface or a bearing shell of the sliding bearing, to access and exchange the bearing pads.
It is also known to provide an opening in the bearing or the support structure to access bearing pads.
This shows the disadvantage the openings, or parts that can be removed, weaken the bearing or the support structure. This leads to additional fatigue of the bearing of the structure.